Solar canopy system

ABSTRACT

A solar canopy has a solar panel assembly including a first solar panel coupled to a second solar panel and oriented non-parallel with respect to the second solar panel. The solar panel assembly has an effective solar-panel-assembly wind loading less than a sum of a first-solar-panel effective wind loading and a second-solar-panel effective wind loading determined individually. An actual load applied by the solar panel assembly to a solar-panel-assembly support structure coupled thereto when the solar panel assembly is subject to a wind loading is less than a design load for the solar panel assembly subject to the wind loading based on a sum of a first-solar-panel net pressure and a second-solar-panel net pressure determined independently.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to U.S. Provisional Patent Application No.62/406,686, filed Oct. 11, 2016 and incorporated herein by reference,and claims the earlier filing date of the provisional application.

COPYRIGHT NOTICE

A portion of the disclosure of this patent document contains materialwhich is subject to copyright protection. The copyright owner has noobjection to the facsimile reproduction by anyone of the patent documentor the patent disclosure, as it appears in the Patent and TrademarkOffice patent file or records, but otherwise reserves all copyrightrights whatsoever.

BACKGROUND OF THE INVENTION

The present invention relates to a solar canopy system and method forreducing canopy support structure design loadings. More particularly,the present invention relates to a solar canopy system having two ormore non-parallel solar panel assemblies having a support structuredesign based on instantaneous time averaging of the measured windloadings of the two or more non-parallel solar panels.

One obstacle to cost reduction of solar photovoltaic (PV) canopystructures is the wind loading prescribed by building codes. Currently,the majority of the canopy structure vendors in the industry do notutilize wind tunnel testing as measuring the wind loading on coplanarpanel assemblies does not yield a useful decrease in loading compared tocode prescribed loads.

The PV canopy structures available openly in the industry havesubstantially the same general configuration as the monoslope free roofPV canopy shown in FIG. 1 and hereafter referred to as the monoslope PVcanopy 1. Generally, the monoslope PV canopy 1 has a vertical post 2extending above a grade 3 and anchored below the grade 3 by a foundation4. One or more solar panels 5 are supported on a beam 6 by purlins 7extending between the panels 5 and the beam 6. The beam 6, in turn, ismounted on the post 2 at an angle θ, such that the total canopyprotected (or horizontal) width W_(H) is less than the total canopypanel width W_(T).

The structure of the monoslope PV canopy 1 may be found in the AmericanSociety of Civil Engineers Standard for Minimum Design Loads forBuildings and Other Structures, ASCE/SEI 7-10 (hereafter referred to asASCE 7-10) in FIGS. 27.4-4 for monoslope free roofs, a portion of whichis reproduced in FIGS. 2A and 2B herein. The direction of the wind γ inFIG. 2A is zero degrees; the direction of the wind γ in FIG. 2B isone-hundred eighty degrees. C_(NW) and C_(NL) are the net pressurecontributions from the top and bottom surfaces for the windward andleeward half of the roof surfaces, respectively. “L” is the horizontallength of the roof measured in the along wind direction. “h” is the meanroof height. 9, is the angle of the plane of the roof from horizontal.The net instantaneous wind loadings C_(NW) and C_(NL) are determined bywind tunnel testing and are provided in ASCE 7-10, FIGS. 27.4-4 for roofangles from zero to forty-five degrees.

It is well accepted within the solar power industry that the windpressures prescribed in ASCE 7-10, FIGS. 27.4-4 are representative ofthe real world loading of these structures. For this reason, the largestsuppliers of PV canopy structures do not typically utilize any windtunnel testing in the design of their products.

The pitched roof PV canopy structure shown in FIG. 3 is one example of astructure with two or more non-parallel planes of solar panel surfaces.Currently, this type of structure is not widely utilized within theindustry although examples do exist. There are several downsides to thisstructure when compared to the structure shown in FIG. 1 includingenergy production (“yield”), direct current (DC) and alternating current(AC) wiring costs, and structural costs. Furthermore, the wind loadingcoefficients prescribed for canopy structures with two or morenon-parallel planes of solar panels can result in higher wind loadingand thus higher costs than the single plane of solar panels design.These coefficients can be seen to be as high for pitched free roofs andtroughed free roofs as for monoslope free roofs (See, ASCE 7-10, FIGS.27.4-5 and FIGS. 27.4-6, not shown herein). As shown diagrammatically inFIG. 3, for non-parallel panel surfaces that are not sufficientlystructurally connected to allow net, instantaneous pressure measurementsacross the total combined area, wind loads F1 and F2 are currentlydetermined separately and the total net wind load F3 is calculated asthe sum of the worst-case F1 and F2 load measurements, which occur atdifferent times. In contrast to the total net wind load F3 shown in FIG.3, the net, instantaneous pressure measurements of the total area ofstructurally connected, non-parallel panel surfaces results in a lowertotal force F3′ as shown in FIG. 4 since in this instance, the loads F1′and F2′ are in opposite directions and occur at the same time.

Accordingly, under current practice, the wind loading coefficientsprescribed for canopy structures with two or more non-parallel planes ofsolar panels (see, FIG. 3) can result in higher wind loading and thushigher costs than the single plane of solar panels designs based on thewind loading coefficients shown in ASCE 7-10, FIGS. 27.4-4. Therefore,there is a need for a design methodology for canopy support structuresfor two or more non-parallel planes of solar panels based on determiningthe net instantaneous wind loading across the total combined area of thenon-parallel planes of solar panels.

BRIEF SUMMARY OF THE INVENTION

Briefly stated, one embodiment of the present invention is directed to asolar canopy including a solar panel assembly and a solar-panel-assemblysupport structure coupled to the solar panel assembly. The solar panelassembly comprises a first solar panel having a total wind-exposedfirst-solar-panel surface area and a second solar panel having a totalwind-exposed second-solar-panel surface area. The second solar panel iscoupled to the first solar panel and oriented non-parallel with respectto the first solar panel. The solar panel assembly has an effectivesolar-panel-assembly wind loading less than a sum of a first-solar-paneleffective wind loading and a second-solar-panel effective wind loadingdetermined individually. The solar-panel-assemble support structureincludes a post having a post bottom end and a post top end spaced fromthe post bottom end. A cross beam is attached to and supported by thepost top end. A plurality of purlins extend between the cross beam andthe first-solar-panel and between the cross beam and thesecond-solar-panel. An actual load applied by the solar panel assemblythrough the purlins and cross beam to the post when the solar panelassembly is subject to a wind loading is less than a design load for thesolar panel assembly subject to the wind loading based on a sum of afirst-solar-panel net pressure for the first solar panel and asecond-solar-panel net pressure for the second solar panel, thefirst-solar-panel net pressure and the second-solar-panel net pressuredetermined independently.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The following detailed description of preferred embodiments of theinvention, will be better understood when read in conjunction with theappended drawings. For the purpose of illustrating the invention, thereis shown in the drawings embodiments which are presently preferred. Itshould be understood, however, that the invention is not limited to theprecise arrangements and instrumentalities shown.

In the drawings:

FIG. 1 is a side elevation view of a prior art canopy comprising aplurality of single, parallel plane photovoltaic solar panels;

FIGS. 2A and 2B are portions of ASCE 7-10, FIGS. 27.4-4 showing the netpressure contributions from the top and bottom surfaces of a monoslopefree roof for the windward and leeward half of the surfaces for atypical application of wind loads as specified in ASCE Standard 7-10;

FIG. 3 is a schematic diagram showing how the net wind load F3 iscurrently evaluated for non-parallel panel surfaces that are notsufficiently structurally connected to allow net, instantaneous pressuremeasurements across the total combined area;

FIG. 4 is a schematic diagram showing a first preferred embodiment ofthe method for determining the net wind load F3′ for non-parallel panelsurfaces in accordance with the present invention;

FIG. 5 is a side elevation view of a preferred embodiment of a solarpanel assembly comprising three non-parallel panel surfaces inaccordance with the present invention;

FIGS. 6A and 6B are schematic diagrams of the solar panel assembly ofFIG. 5 showing maximum and minimum wind loading, respectively;

FIG. 7 is a side elevation view of a preferred embodiment of a solarpanel assembly comprising four non-parallel panel surfaces in accordancewith the present invention;

FIG. 8 is a side elevation view of a preferred embodiment of a solarpanel assembly comprising six non-parallel panel surfaces in accordancewith the present invention;

FIG. 9 is an enlarged portion of the solar panel assembly of FIG. 8;

FIG. 10 is a top view of the solar panel assembly of FIG. 8;

FIG. 11 is a right side elevation view of the solar panel assembly ofFIG. 8; and

FIG. 12 is a top perspective view of the solar panel assembly of FIG. 8.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to embodiments of the invention,examples of which are illustrated in the accompanying drawings. Theterminology used in the description of the invention herein is for thepurpose of describing particular embodiments only and is not intended tobe limiting of the invention.

As used in the description of the invention and the appended claims, thesingular forms “a”, “an” and “the” are intended to include the pluralforms as well, unless the context clearly indicates otherwise. The words“and/or” as used herein refers to and encompasses any and all possiblecombinations of one or more of the associated listed items. The words“comprises” and/or “comprising,” when used in this specification,specify the presence of stated features, integers, steps, operations,elements, and/or components, but do not preclude the presence oraddition of one or more other features, integers, steps, operations,elements, components, and/or groups thereof.

The words “right,” “left,” “lower” and “upper” designate directions inthe drawings to which reference is made. The words “inwardly” and“outwardly” refer to directions toward and away from, respectively, thegeometric center of the solar canopy, and designated parts thereof. Theterminology includes the words noted above, derivatives thereof andwords of similar import.

Although the words first, second, etc., are used herein to describevarious elements, these elements should not be limited by these words.These words are only used to distinguish one element from another. Forexample, a first panel could be termed a second panel, and, similarly, apanel tube could be termed a first panel, without departing from thescope of the present invention.

As used herein, the words “if” may be construed to mean “when” or “upon”or “in response to determining” or “in response to detecting,” dependingon the context. Similarly, the phrase “if it is determined” or “if [astated condition or event] is detected” may be construed to mean “upondetermining” or “in response to determining” or “upon detecting [thestated condition or event]” or “in response to detecting [the statedcondition or event],” depending on the context.

The following description is directed towards various embodiments of asolar canopy in accordance with the present invention.

Referring to the drawings in detail, where like numerals indicate likeelements throughout, there is shown in FIGS. 5 and 6 a first preferredembodiment of the solar canopy, generally designated 10, and hereinafterreferred to as the “canopy” 10 in accordance with the present invention.

The canopy 10 comprises a three panel (or 3P) solar panel assembly 12supported by and coupled to a solar-panel-assembly support structure 14as further described below. The solar panel assembly 12 comprises atleast a first solar panel 16 with a total wind-exposed first-solar-panelsurface area and a second solar panel 18 with a total wind-exposedsecond-solar-panel surface area. The solar panel assembly 12 may have athird solar panel 20 with a total wind-exposed third-solar-panel surfacearea. Preferably, the solar panel assembly 12 has a rectilinear array ofsolar panels including the first, second and third solar panels 16, 18,20. The total number of solar panels comprising the array is a designchoice based on the desired electrical output of the assembly.Typically, the solar panel assembly 12 includes at least adjacent sixrows with three panels per row but could have more than six rows or lessthan six rows without departing from the spirit of the invention.

The second solar panel 18 is coupled to the first solar panel 16 suchthat the second solar panel 18 is oriented non-parallel with respect tothe first solar panel 16. The third solar panel 20 is orientednon-parallel with respect to the second solar panel 18. The manner inwhich the panels 16, 18, 20 are coupled to each other can be by any of anumber of well known couplings used in the solar canopy industry, is notpart of the claimed invention and for brevity is not disclosed herein.Preferably the first and second solar panels 16, 18 are tilted about 5-7degrees from the horizontal, the first solar panel 16 being tilted in acounter clockwise direction and the second solar panel being tilted in aclockwise direction. The degree of tilt can be more or less than theabout 5-7 degrees without departing from the spirit of the invention.However, the tilt angle could be less than five degrees or more thanseven degrees without departing from the spirit of the invention. Thethird solar panel 20 may be tilted parallel to the first solar panel;alternatively, the third solar panel 20 may be oriented non-parallelwith respect to the first solar panel 16 and tilted in the counterclockwise direction at an angle different than the tilt angle of thefirst solar panel 16.

The solar panel assembly 12 has an effective solar-panel-assembly windloading less than a sum of a first-solar-panel effective wind loadingand a second-solar-panel effective wind loading determined individually.The effective solar-panel-assembly wind loading is determined by windtunnel testing of the solar panel assembly 12 whereby instantaneous timeaveraging of the measured pressures of two or more non-parallel solarpanel assemblies determines the net wind loading as further discussedbelow.

The solar-panel-assembly support structure 14 comprises a post 30 havinga post bottom end 32 and a post top end 34 spaced from the post bottomend 32. A cross beam 36 is attached to and supported by the post top end34. The post bottom end 32 may be embedded directly in the ground 38.Preferably, but not necessarily, the post bottom end 32 is attached to afoundation 40 in the ground 38. A plurality of purlins 42 extend betweenthe cross beam 36 and the first, second and third solar panels 16, 18,20 and support and attach the first, second and third solar panels 16,18, 20 to the cross beam 36. The purlins 42 vary in length in order toachieve the desired tilt of the solar panels 16, 18, 20. The purlins 42can have a variety of well known geometric shapes and are typicallyroll-formed shapes.

The actual load applied by the solar panel assembly 12 through thepurlins 42 and cross beam 36 to the post 30 when the solar panelassembly 12 is subject to a wind loading is less than a design load forthe solar panel assembly 12 subject to the wind loading based on a sumof a first-solar-panel net pressure for the first solar panel, asecond-solar-panel net pressure for the second solar panel, and athird-solar-panel net pressure load for the third solar panel, when thefirst-solar-panel net pressure, the second-solar-panel net pressure andthe third-solar-panel net pressure load are determined independently.See, FIGS. 5, 6A and 6B.

FIG. 7 shows another preferred embodiment of the solar canopy, generallydesignated 100, and hereinafter referred to as the “canopy” 100 inaccordance with the present invention. The canopy 100 (also designated a4P canopy) has substantially the same structure as the canopy 10disclosed above but for a fourth solar panel 122. Similar to the canopy10, the canopy 100 has a solar panel assembly 112 comprising solarpanels oriented non-parallel with respect to adjacent solar panels.

FIGS. 8-12 show still another preferred embodiment of the solar canopy,generally designated 200, and hereinafter referred to as the “canopy”200 in accordance with the present invention. The canopy 200 (alsodesignated a 6P canopy) has substantially the same structure as thecanopy 10 and the canopy 100 disclosed above with the exception that thecanopy 200 has a solar panel assembly 212 comprising a plurality of rowsof six solar panel 216, 218, 220, 222, 224, 226 and the due to the sizeof the solar panel assembly support structure 214 comprises a pluralityof beams 236 coupled to the solar panels by a plurality of mini-zeepurlins 242 and is supported by two posts 230 (See, FIGS. 10-12).Referring to FIG. 9, the purlins 242 may vary in length and gaugedepending on the distribution of the wind loading over the surface ofthe array solar panels.

Although three preferred embodiments of solar canopies in accordancewith the present invention have been disclosed, the invention is notlimited to these three canopies. The size of the solar panel assembly isa design choice based on the desired electrical output of the assembly.Other embodiments may include more than rows of six solar panels or lessthan rows of six solar panels within the spirit of the invention.Similarly, the number and distribution of the posts, cross beams andpurlins comprising the solar-panel-assembly support structure is basedon determining the net instantaneous wind loading across the totalcombined area of the non-parallel planes of solar panels.

The design methodology for the foregoing canopy support structureshaving two or more non-parallel planes of solar panels is based ondetermining the net instantaneous wind loading across the total combinedarea of the non-parallel planes of solar panels. Referring to FIGS. 7Aand 7B, force coefficient GC_(P) and moment coefficients GC_(MHy),GC_(My) defined by the following equations are calculated from windtunnel pressure data and are used to size all components of thesolar-panel-assembly support structure.

$\begin{matrix}{{GC}_{P} = \frac{F_{normal}}{q_{H} \cdot A}} & {{Eq}.\mspace{14mu} 1} \\{{GC}_{{MH}_{y}} = \frac{M_{{{top}\_{of}}{\_{post}}}}{q_{H} \cdot A \cdot L}} & {{Eq}.\mspace{14mu} 2} \\{{GC}_{M_{y}} = \frac{M_{grade}}{q_{H} \cdot A \cdot L}} & {{Eq}.\mspace{14mu} 3}\end{matrix}$

Where,

-   -   F_(normal) is the force normal to the top surface of the PV        modules;    -   M_(top) _(_) _(of) _(_) _(post) is the moment about the top of        post (center of the cross beam);    -   M_(grade) is the moment about the grade.    -   q_(H) is the ASCE 7 velocity pressure at a height (H) of ≤4.5 m        in open terrain;    -   A is the averaging area (No. of panels multiplied by 2 m²); and    -   L is the nominal chord length (6 m for 3P System, 8 m for 4 P        System, and 12 m for 6P System).

The wind tunnel pressure data is obtained by simultaneously measuringthe pressure at pressure taps embedded in the surfaces of panelscomprising the solar panel assembly to be supported by thesolar-panel-assembly support structure.

It will be appreciated by those skilled in the art that changes could bemade to the embodiments described above without departing from the broadinventive concept thereof. It is understood, therefore, that thisinvention is not limited to the particular embodiments disclosed, but itis intended to cover modifications within the spirit and scope of thepresent invention as defined by the appended claims.

We claim:
 1. A solar canopy comprising: a solar panel assemblycomprising: a first solar panel having a total wind-exposedfirst-solar-panel surface area; and a second solar panel having a totalwind-exposed second-solar-panel surface area, wherein the second solarpanel is coupled to the first solar panel and has a fixed non-parallelorientation with respect to the first solar panel, and wherein the solarpanel assembly has an effective solar-panel-assembly wind loading lessthan a sum of a first-solar-panel effective wind loading and asecond-solar-panel effective wind loading determined individually; and asolar-panel-assembly support structure coupled to the solar panelassembly, the solar-panel-assemble support structure comprising: a posthaving a post bottom end and a post top end spaced from the post bottomend; a cross beam attached to and supported by the post top end; and aplurality of purlins extending between the cross beam and thefirst-solar-panel and between the cross beam and the second-solar-panel,wherein the solar-panel-assembly support structure is designed tosupport an actual load applied to the solar-panel-assembly supportstructure by the solar panel assembly when the solar panel assembly issubject to a wind loading that is less than a design load for the solarpanel assembly subject to the wind loading based on a sum of afirst-solar-panel net pressure for the first solar panel and asecond-solar-panel net pressure for the second solar panel, thefirst-solar-panel net pressure and the second-solar-panel net pressuredetermined independently wherein the actual load is obtained bysimultaneously measuring a pressure at a plurality of taps embedded in asurface of the first and second solar panels.
 2. The solar canopy ofclaim 1, wherein the solar panel assembly has a third solar panel with atotal wind-exposed third-solar-panel surface area, the third solar panelcoupled to the second solar panel and oriented non-parallel with respectto the second solar panel.
 3. The solar canopy of claim 2, wherein thesolar panel assembly is a rectilinear array of a plurality of solarpanels including the first solar panel, the second solar panel and thethird solar panel.
 4. The solar canopy of claim 3, wherein therectilinear array comprises at least an adjacent six rows with threesolar panels of the plurality of solar panels per row.
 5. The solarcanopy of claim 1, wherein the first solar panel and second solar panelare tilted at a tilt angle of about five degrees to about seven degreesfrom the horizontal, the first solar panel being tilted in a counterclockwise direction and the second solar panel being tilted in aclockwise direction.
 6. The solar canopy of claim 5, wherein the solarpanel assembly has a third solar panel with a total wind-exposedthird-solar-panel surface area, the third solar panel coupled to thesecond solar panel and tilted parallel to the first solar panel.
 7. Thesolar canopy of claim 5, wherein the solar panel assembly has a thirdsolar panel with a total wind-exposed third-solar-panel surface area,the third solar panel coupled to the second solar panel, orientednon-parallel with respect to the first solar panel and tilted in thecounter clockwise direction at another tilt angle different than thetilt angle of the first solar panel.
 8. The solar canopy of claim 1,wherein the actual load applied to the solar-panel-assembly supportstructure is determined by a force coefficient GC_(P), a first momentcoefficient GC_(MHy), and a second moment coefficient GC_(My) defined bythe following equations: $\begin{matrix}{{GC}_{P} = \frac{F_{normal}}{q_{H} \cdot A}} \\{{GC}_{{MH}_{y}} = \frac{M_{{top\_ of}{\_ post}}}{q_{H} \cdot A \cdot L}} \\{{GC}_{M_{y}} = \frac{M_{grade}}{q_{H} \cdot A \cdot L}}\end{matrix}$ Where, F_(normal) is a force normal to a top surface ofthe first or second solar panels; M_(top) _(_) _(of) _(_) _(post) is amoment about a top of the post (center of a cross beam); M_(grade) is amoment about a bottom of the post; q_(H) is a velocity pressure at aheight (H) of ≤4.5 m in an open terrain; A is a averaging area (Numberof panels multiplied by 2 m²); and L is a nominal chord length, andwherein the force coefficient GC_(P), the first moment coefficientGC_(MHy), and the second moment coefficient GC_(My) are calculated fromwind tunnel pressure data obtained by simultaneously measuring apressure at a plurality of pressure taps embedded in a surface of thefirst and second solar panels.
 9. The solar canopy of claim 1, whereinthe plurality of purlins extend substantially vertically between thecross beam and the first-solar-panel and between the cross beam and thesecond-solar-panel and varying in length to achieve a desired tilt ofthe first and second solar panels.